In the area of photovoltaics, the active photovoltaic (“PV”) cell in many cases has metallic conductor lines on the front, sun-facing, surface of the cell. These conductor lines are essential to the electrical circuit of which the PV cell is an element. However, at the same time, these front side metallic conductor lines cause a portion of the incident solar radiation to be blocked from entering the active semiconductor absorber materials in the cell, and therefore do not contribute to the photovoltaic current produced by the cell.
These optical losses in photovoltaic conversion due to the presence of front side conductor lines are found in many different types of photovoltaics, from PV modules designed for use at 1 kW/m2 irradiance (where 1 kW/m2 is approximately the irradiance of the sun at the surface of the earth) to concentrating photovoltaic (“CPV”) modules in which the solar radiation is concentrated to 5, 50, or even greater than 500 times the irradiance of the sun and focused on higher efficiency PV cells.
In an effort to overcome the loss of electrical power from the PV module due to obscuration of the front side of the PV cell by the front side conductors some PV cells dispose all the cell conductor lines away from the front side of the PV cell. These approaches are typically referred to as “back side contacting PV cells”, and require extensive redesign of the PV cell with increased complexity and cost.
In others areas, such as in LCD display devices and LED lighting devices, there is a need to decrease the spatial modulation of light to provide more uniform illumination from the devices.
Accordingly, in view of the foregoing it is believed to be advantageous to provide an article in the form of an optical element which could be used in conjunction with a photovoltaic, LCD and/or LED device and which serves to harvest substantially all of the radiation incident on the article and which is also able to redirect that incident light toward or away from certain regions of interest on the device.
Such an article, when used in conjunction with a photovoltaic cell, could redirect the light away from the front side conductor lines and towards the active semiconductor materials of the PV cell, so that this light will contribute to the electrical output of a PV cell, module and system.
When used in conjunction with an LCD display and/or LED lighting device, such an article could be used to provide more uniform illumination in otherwise dark regions of the LCD display device. In the LED lighting case the optical element may be used to make the point source-like-nature of the LED more homogeneous and uniform.